a lot of flare using PENTAX 645 lenses

[gustavo_xavier]

I've been using a 35mm, a 55mm, a 75mm and a 120mm PENTAX 645 lenses on my

Canon 1Ds2 35mm digital camera, using a ZORK Adaptor.

 

The main problem is the very large flare that I've got using this combination.

I have to be very careful with any light source beside or in front of the

lenses. When the light is beside to the camera it's easy to solve the problem

by blocking the light. But when it's in front of the camera, a window i.e,

it's impossible to cut it off.

 

Is it normal? How are the results using this lenses on a PENTAX 645 body?

[godfrey]

I've used A35, A45, A75 and A120 645 lenses, haven't had any problems with flare. Are you

using a lens hood matched to the FoV of these focal lengths on the 1Ds II?

 

Godfrey

[gustavo_xavier]

Yes, Godfrey. I've been using all this lenses with the PENTAX hoods.

[godfrey]

Gustavo,

 

The Pentax hoods for these lenses are designed for 645 format and do not provide efficient flare

prevention for a 24x36mm format camera. 24x36 mm is approximately a 1.62x crop of the 645

format: you need hoods designed for the FoV of a 35mm camera's 35, 75 and 120mm lenses, not

the OEM Pentax hoods.

 

The image circle of these lenses is so large compared to the 24x36mm format that you could be

getting internal body reflections without a proper, efficient lens hood for the reduced size

format.

 

I use these lenses only on a Pentax 645 camera, where the OEM Pentax hoods work well.

 

Godfrey

[gustavo_xavier]

Godfrey,

 

In this case I must find a "closer" hood for each lens. Have you ever use the Lindahl Shades or the Lee Shades?

 

Thanks!

[david_dorcich1]

The smaller sensor on the 1Ds2 is just making a crop out of the image circle. A smaller hood won't solve this problem, if that was the case you would see a flare problem when using the lens on the 645, the flare would be in the center area of the image, you are just using this area only by mounting the lens on the cannon.

 

Flaring is a property of the lens, the propensity of flare doesn't change when you stick a smaller format camera on the lens.

[godfrey]

<center>

<a href="http://homepage.mac.com/ramarren/photo/PAW6/large/39-half.jpg"

target=new1>

<img src="http://homepage.mac.com/ramarren/photo/PAW6/large/39.jpg" border=0>

</a><br>

Skull Valley Station - Utah, November 2006<br>

<i>©2006 by Godfrey DiGiorgi<br>

Pentax 645 + A35mm f/3.5<br>

<br>

Click image above for a larger rendering in a new window.</i>

<br></center><br>

That's not true, David, IF the flare being seen is the result of a reflection off bits in the

mirror box. I have seen this quite often with medium and large format lenses when I use

them with smaller format cameras through adaptation.

<br><br>

It's worth a try. I haven't seen Gustavo's photos to see what kind of flare he's reporting;

I've not seen flare with smc Pentax 645 lenses, however, unless there is a poor quality filter

fitted. I don't use filters; that is another possibility for why he might be seeing flare.

<br><br>

The 645 photo above should certainly have shown flare due to the bright light sources in

the image field if it were going to happen, I didn't clone any out.

<br><br>

Godfrey

<br>

[gustavo_xavier]

I?m sending you an example of this flare.<div></div>

[gustavo_xavier]

Another image showing the same problem. I don't use any filters.<div></div>

[gustavo_xavier]

The 2 photos again.<div></div>

[gustavo_xavier]

The second.<div></div>

[gustavo_xavier]

The flare happens always in the center of the image, appearing as a white area.

[godfrey]

I still suspect that you're getting internal reflections from the small mirror box. Make up a

paper lens hood with matte black paper and keep extending it until it vignettes, then

shorten it. See if you get the same flare.

 

Otherwise, you might have fungus or other problems inside your lens.

 

I don't get anything like this on the Pentax 645.

 

Godfrey

[godfrey]

Gustavo,

 

It occurred to me that you might be also getting back reflection from the sensor to the lens.

 

Godfrey

[jeff_drew4]

I think generalizing that all P645 lenses have flare issues points toward camera and/or adapter combo as part of the cause. I have the 35, 75 and 120mm lenses and have used them on K1000 film bodies with no issues. I will admit to being less partial to the 35mm on a 35mm body 'cuz the standard 35mm model lens is sharper. Would it be possible to test the theory of body/adapter issue by shooting the same image with multiple formats: 1 as digital and 1 as film? Then compare and analyze.

[godfrey]

Jeff,

 

I don't think there was anyone generalizing about P645 lenses and flare. Gustavo's

problem is specific: 35, 55, 75 and 120 mm P645 lenses on a Canon 1Ds II. DSLR bodies

will show back reflection where film bodies will not.

 

I haven't used any of the P645 lenses on DSLR bodies (I don't have the necessary adapters)

but it could also be specific to the characteristics of the Canon 1Ds II as well.

 

Tricky stuff. :-)

 

Godfrey

[User_503771]

Don't rule out flare caused by light bouncing around inside the camera! The Kiev medium format cameras are notorious for it and flocking kits are essential.

 

Also, it *does* make sense that a "calibrated" lens shade could just do the trick by limiting or eliminating the out-of-field light bouncing around. If the light is not coming in through the lens anymore, it won't bounce! This is one of the old view camera tricks.

 

Is it also possible that the adaptor is contributing to flare?

[gustavo_xavier]

I'm gonna do some tests with the adaptor in different positions, using narrow black paper hoods, differents apertures, and I'll show you as soon as possible.

 

Could it be a lens's coating flaw?

 

Thank you again.

[jim_rais]

<p align="justify">

<I>Could it be a lens's coating flaw?</I><BR>

<BR>All of it? I doubt it. Pentax is one of those companies which is known for using the better sort multi coating (if not the first in the row), hence the abbreviation of SMC (Super Multi Coating) on their older, 645 and 67 lenses.<P>

[dave_bazzel1]

Since the lenses you are using are designed to cover a larger film area I would guess the light is reflecting onto the adapter. Something to consider anyway. Dave. www.davebazzel.com

[gustavo_xavier]

I've done some test with black papers and I think it's not lens problem. The flare is being created by lights that can't be blocked by the dedicated lens hood. I shoot interiors and it always have a lot of light sources in all directions. As some guys suggested, I need "closers" lens hood to use with this medium format lenses on a 35mm camera, instead of using the dedicated lens hoods.

 

Have you ever used the Lindahl or Lee Shades attatched to this lenses?

 

BTW, Happy New Year everyone!

 

Thanks.

[audun_sjoeseth1]

The shape of the adapter is important too awoid reflections from the adapter towards the sensor of the camera.

 

I have used the P-645-A 150/3.5 and the A 75/2.8 with the Pentax 645-K adapter on my K10D without any problems like this.

[xato]

I would take a regular Canon film body, put on the P645 lens and adapter, open up the back, put shutter on "B" and take a look at the inside of the mirror box chamber. I'd bet dollars to donuts that the larger P645 film image would be brightening up the sides of the mirror box and therefore reflecting back onto the sensor, giving a central hot spot.

 

I haven't seen any flare on any of my P645 lens.

 

Warren